package UDP.UDP1;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
//服务器
public class UdpEchoServer {
    private DatagramSocket socket;
    public UdpEchoServer(int port) throws SocketException {
        socket = new DatagramSocket(port);
    }
    public void start() throws IOException {
        System.out.println("服务器启动!");
        while(true) {
            //1.接收请求
            DatagramPacket requestPacket = new DatagramPacket(new byte[4096], 4096);
            socket.receive(requestPacket);
            //2.根据请求计算响应
            String request = new String(requestPacket.getData(), 0, requestPacket.getLength());
            String response = process(request);
            //3.向客户端返回响应
            DatagramPacket responsePacket = new DatagramPacket(response.getBytes(),
                    response.getBytes().length, requestPacket.getSocketAddress());
            socket.send(responsePacket);
            //4.转化成日志
            System.out.printf("[%s:%s] req: %s; resp: %s\n",requestPacket.getAddress().toString(),
                    requestPacket.getPort(), request, response);
        }
    }

    private String process(String request) {
        return request;
    }
    public static void main(String[] args) throws IOException {
        UdpEchoServer server = new UdpEchoServer(9090);
        server.start();;
    }

}
